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Author Sobolewski, Roman; Xu, Ying; Zheng, Xuemei; Williams, Carlo; Zhang, Jin; Verevkin, Aleksandr; Chulkova, Galina; Korneev, Alexander; Lipatov, Andrey; Okunev, Oleg; Smirnov, Konstantin; Gol'tsman, Gregory N.
Title Spectral sensitivity of the NbN single-photon superconducting detector Type Journal Article
Year 2002 Publication IEICE Trans. Electron. Abbreviated Journal IEICE Trans. Electron.
Volume E85-C Issue 3 Pages 797-802
Keywords NbN SSPD, SNSPD
Abstract We report our studies on the spectral sensitivity of superconducting NbN thin-film single-photon detectors (SPD's) capable of GHz counting rates of visible and near-infrared photons. In particular, it has been shown that a NbN SPD is sensitive to 1.55-µm wavelength radiation and can be used for quantum communication. Our SPD's exhibit experimentally measured intrinsic quantum efficiencies from 20% at 800 nm up to 1% at 1.55-µm wavelength. The devices demonstrate picosecond response time (<100 ps, limited by our readout system) and negligibly low dark counts. Spectral dependencies of photon counting of continuous-wave, 0.4-µm to 3.5-µm radiation, and 0.63-µm, 1.33-µm, and 1.55-µm laser-pulsed radiations are presented for the single-stripe-type and meander-type devices.
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Call Number Serial 1531
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Author Beck, Matthias; Leiderer, Paul; Kabanov, Viktor V.; Gol'tsman, Gregory; Helm, Manfred; Demsar, Jure
Title Energy-gap dynamics of a superconductor NbN studied by time-resolved terahertz spectroscopy Type Abstract
Year 2012 Publication INIS Abbreviated Journal INIS
Volume 45 Issue 12 Pages 1-3
Keywords NbN energy gap
Abstract Using time-resolved terahertz (THz) spectroscopy we performed direct studies of the photoinduced suppression and recovery of the SC gap in a conventional SC NbN. Both processes are found to be strongly temperature and excitation density dependent. The analysis of the data with the established phenomenological Rothwarf-Taylor model enabled us to determine the important microscopic constants: the Cooper pair-breaking rate via phonon absorption and the bare quasiparticle recombination rate. From the latter we were able to extract the dimensionless electron-phonon coupling constant, λ=1.1±0.1, in excellent agreement with theoretical estimates. The technique also allowed us to determine the absorbed energy required to suppress SC, which in NbN equals the thermodynamic condensation energy (in cuprates the two differ by an order of magnitude). Finally, we present the first studies of dynamics following resonant excitation with intense narrow band THz pulses tuned to above and below the superconducting gap. These suggest an additional process, particularly pronounced near Tc, that could be attributed to amplification of SC via effective quasiparticle cooling.
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Call Number Serial 1383
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Author Hübers, Heinz-Wilhelm; Semenov, Alexei; Schubert, Josef; Gol'tsman, Gregory; Voronov, Boris; Gershenzon, Evgeni
Title Performance of the phonon-cooled hot-electron bolometric mixer between 0.7 THz and 5.2 THz Type Conference Article
Year 2000 Publication Proc. 8-th Int. Conf. on Terahertz Electronics Abbreviated Journal Proc. 8-th Int. Conf. on Terahertz Electronics
Volume Issue Pages 117-119
Keywords NbN HEB mixers
Abstract We report on the phonon cooled NbN hot electron bolometer as mixer in the terahertz frequency range. Its hybrid antenna consists of a hyperhemispheric silicon lens and a logarithmic-spiral feed antenna. Noise temperatures have been measured between 0.7 THz and 5.2 THz. A quarter wavelength layer of Parylene works as antireflection coating for the silicon lens and reduces the noise temperature by about 30. It was found that the antenna pattern at 2.5 THz is determined by the feed antenna and not by the diameter of the lens.
Address Darmstadt, Germany
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Area Expedition Conference International Conference on Terahertz Electronics [8th], Held inDarmstadt, Germany on 28-29 September 2000
Notes Approved no
Call Number Serial 1553
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Author Rosfjord, Kristine M.; Yang, Joel K. W.; Dauler, Eric A.; Kerman, Andrew J.; Vikas Anant; Voronov, Boris M.; Gol'tsman, Gregory N.; Berggren, Karl K.
Title Nanowire Single-photon detector with an integrated optical cavity and anti-reflection coating Type Journal Article
Year 2006 Publication Opt. Express Abbreviated Journal Opt. Express
Volume 14 Issue 2 Pages 527-534
Keywords SSPD, SNSPD, cavity
Abstract We have fabricated and tested superconducting single-photon detectors and demonstrated detection efficiencies of 57% at 1550-nm wavelength and 67% at 1064 nm. In addition to the peak detection efficiency, a median detection efficiency of 47.7% was measured over 132 devices at 1550 nm. These measurements were made at 1.8K, with each device biased to 97.5% of its critical current. The high detection efficiencies resulted from the addition of an optical cavity and anti-reflection coating to a nanowire photodetector, creating an integrated nanoelectrophotonic device with enhanced performance relative to the original device. Here, the testing apparatus and the fabrication process are presented. The detection efficiency of devices before and after the addition of optical elements is also reported.
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ISSN 1094-4087 ISBN Medium
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Notes PMID:19503367 Approved no
Call Number Serial 388
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Author Divochiy, Aleksander; Marsili, Francesco; Bitauld, David; Gaggero, Alessandro; Leoni, Roberto; Mattioli, Francesco; Korneev, Alexander; Seleznev, Vitaliy; Kaurova, Nataliya; Minaeva, Olga; Gol'tsman, Gregory; Lagoudakis, Konstantinos G.; Benkhaoul, Moushab; Lévy, Francis; Fiore, Andrea
Title Superconducting nanowire photon-number-resolving detector at telecommunication wavelengths Type Journal Article
Year 2008 Publication Nat. Photon. Abbreviated Journal Nat. Photon.
Volume 2 Issue 5 Pages 302-306
Keywords SSPD, photon-number-resolving
Abstract Optical-to-electrical conversion, which is the basis of the operation of optical detectors, can be linear or nonlinear. When high sensitivities are needed, single-photon detectors are used, which operate in a strongly nonlinear mode, their response being independent of the number of detected photons. However, photon-number-resolving detectors are needed, particularly in quantum optics, where n-photon states are routinely produced. In quantum communication and quantum information processing, the photon-number-resolving functionality is key to many protocols, such as the implementation of quantum repeaters1 and linear-optics quantum computing2. A linear detector with single-photon sensitivity can also be used for measuring a temporal waveform at extremely low light levels, such as in long-distance optical communications, fluorescence spectroscopy and optical time-domain reflectometry. We demonstrate here a photon-number-resolving detector based on parallel superconducting nanowires and capable of counting up to four photons at telecommunication wavelengths, with an ultralow dark count rate and high counting frequency.
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Notes Approved no
Call Number Serial 916
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